Hello all,
I recently picked up a blown MTX 2300x strictly for a learning project as I have taken a recent interest in amplifier design. I am still quite new to this, so please bear with me...
The original owner was hooking up a capacitor when the amp blew.
I hooked up the amp on my bench with no input, and no speakers hooked up and read 44VDC across the left channel. It would read 44VDC for 2-3 seconds, drop to 0V for about 1 second, then continue repeating the cycle.
I took the amp apart and found one shorted fet on the left channel.
I removed the 4 fets in that group (center row, top) and tested the amp again (is this a bad idea?)
Now with the fets removed on the left channel I powered up the amp to see if there was any output on the right channel. It was very weak and severly distorted, could this be due to the fact the fets on the left channel are removed?
Also, the fan does not start for some reason, before I removed the fets the fan worked, but was super noisy. I am not sure if it is activatedy by a rise in temp. or not.
I am going to remove the rest of the fets tonight and test for shorts.
Are there any other tests I can perform on the amp before I solder in some new parts? I dont want to replace them all again. Anything else I can test while I have it apart?
Thanks for any help.
I recently picked up a blown MTX 2300x strictly for a learning project as I have taken a recent interest in amplifier design. I am still quite new to this, so please bear with me...
The original owner was hooking up a capacitor when the amp blew.
I hooked up the amp on my bench with no input, and no speakers hooked up and read 44VDC across the left channel. It would read 44VDC for 2-3 seconds, drop to 0V for about 1 second, then continue repeating the cycle.
I took the amp apart and found one shorted fet on the left channel.
I removed the 4 fets in that group (center row, top) and tested the amp again (is this a bad idea?)
Now with the fets removed on the left channel I powered up the amp to see if there was any output on the right channel. It was very weak and severly distorted, could this be due to the fact the fets on the left channel are removed?
Also, the fan does not start for some reason, before I removed the fets the fan worked, but was super noisy. I am not sure if it is activatedy by a rise in temp. or not.
I am going to remove the rest of the fets tonight and test for shorts.
Are there any other tests I can perform on the amp before I solder in some new parts? I dont want to replace them all again. Anything else I can test while I have it apart?
Thanks for any help.
An externally hosted image should be here but it was not working when we last tested it.
Argh
I've been repairing MTX amplifiers since they came out (back when PPI was building them). I HIGHLY recommend sending any 2300 or 2300x in to MTX for repair. I spent a month rebuilding one only to have it go up in smoke the second I turned it on. It's much easier to pay MTX $100 plus shipping, and its well worth it.
The fan is shot. It is temp controlled, but always spins up a bit. There is more going on with the amp than just an improper connection. It sounds as though it was severly abused electrically.
I've been repairing MTX amplifiers since they came out (back when PPI was building them). I HIGHLY recommend sending any 2300 or 2300x in to MTX for repair. I spent a month rebuilding one only to have it go up in smoke the second I turned it on. It's much easier to pay MTX $100 plus shipping, and its well worth it.
The fan is shot. It is temp controlled, but always spins up a bit. There is more going on with the amp than just an improper connection. It sounds as though it was severly abused electrically.
PPMTX amps
PPI made amplifiers for a number of companies during the late 80's/early 90's. Such as:
G&S Designs
MTX
Audio Art
PSL
Sedona (was PPI's lower end line sold to PSL)
and a few others
PPI always used a chassis-mounting design that used the bottom plate to hold the power transistors in place. Every amp PPI made used this technique, which was probably the best advancement in car audio reliability.
The old Blue Thunder and Terminator Series were PPIs regular and ProMos series, respectively. MTX started designing their own amps, the Thunder Series in 1994 with the introduction of the 2XXX/4XXX series. These did not have crossovers built in, were Pure N channel MosFet output and were very clean and reliable. These amps put MTX on the map, to be sure.
IIRC, The next year they reintroduced the Blue Thunder Amplifiers using the same chassis and design as the Thunder Amplifiers. In fact, there was no difference between the regular and the Blues except for a modified logo and paint color (a hideous grey/blue). That same year, they also had the Black Gold amplifier that had a very distinct appearance. MTX did not design/build this one, and there is still some debate about who made this one for them. It appears to be a mix between Phoenix Gold and PPI. Nevertheless, it was MTX's best amplifier line ever. It was virtually indestructible and had massive headroom. Unfortunately, the kids didn't buy enough and the model was discontinued the next year.
That's about all I've got in my head as far as the amps go.
P.S. Their Class D amplifiers have had serious problems since Day One with the D500. Buyer Beware.
PPI made amplifiers for a number of companies during the late 80's/early 90's. Such as:
G&S Designs
MTX
Audio Art
PSL
Sedona (was PPI's lower end line sold to PSL)
and a few others
PPI always used a chassis-mounting design that used the bottom plate to hold the power transistors in place. Every amp PPI made used this technique, which was probably the best advancement in car audio reliability.
The old Blue Thunder and Terminator Series were PPIs regular and ProMos series, respectively. MTX started designing their own amps, the Thunder Series in 1994 with the introduction of the 2XXX/4XXX series. These did not have crossovers built in, were Pure N channel MosFet output and were very clean and reliable. These amps put MTX on the map, to be sure.
IIRC, The next year they reintroduced the Blue Thunder Amplifiers using the same chassis and design as the Thunder Amplifiers. In fact, there was no difference between the regular and the Blues except for a modified logo and paint color (a hideous grey/blue). That same year, they also had the Black Gold amplifier that had a very distinct appearance. MTX did not design/build this one, and there is still some debate about who made this one for them. It appears to be a mix between Phoenix Gold and PPI. Nevertheless, it was MTX's best amplifier line ever. It was virtually indestructible and had massive headroom. Unfortunately, the kids didn't buy enough and the model was discontinued the next year.
That's about all I've got in my head as far as the amps go.
P.S. Their Class D amplifiers have had serious problems since Day One with the D500. Buyer Beware.
Thanks for the suggestion, but to be honest I picked this amp up as a learning project, so if I can't get it up and running again, no big deal.
I removed the fan and hooked it up to a power supply, and it works fine. I also had a look at a couple other 2300x's and they fans did not come on when the amp was turned on.
Im going to try and rebuild it once, and if it goes up in smoke I'll consider sending it in (if it doesn't explode on the bench ).
I removed the fan and hooked it up to a power supply, and it works fine. I also had a look at a couple other 2300x's and they fans did not come on when the amp was turned on.
Im going to try and rebuild it once, and if it goes up in smoke I'll consider sending it in (if it doesn't explode on the bench
).
Hey guys...
Seems like there is some knowledge here on PPI amps....and I need some help. I bought two A600's recently off ebay (risky I know). These were replacements for an ADS 860MX. At any rate I am having some strange problems with them. First I am running both at normal two channel 4 ohm load to Infinity Ref's 4X6's and two eclipse 6-1/2" drivers. There is a large descrepancy in output between the two. The A600 running the two front 4X6's is very strong and the second A600 running any kind of speaker is roughly half the first.
Both have 13.5 voltage sometimes 14 at vehicle startup. In addition the strong A600 (powering the 2 4x6's) gets extremely hot and makes a low grade buzzing noise fom inside the amp. Both amps display the normal LEDS with no yellow leds on. The strong amp works great and sounds great but I am concerned about the heat and noise. The other A600 stays cool but just doesn't put out. I have swapped RCA's and speakers....no difference. I also am running an A1200 which is working fine. All amps have their own seperate short grounds and power supplies which are 8 guage.
Can someone help me out? Is my alternator the problem? How can I diagnose this problem? I do I repair it?
Seems like there is some knowledge here on PPI amps....and I need some help. I bought two A600's recently off ebay (risky I know). These were replacements for an ADS 860MX. At any rate I am having some strange problems with them. First I am running both at normal two channel 4 ohm load to Infinity Ref's 4X6's and two eclipse 6-1/2" drivers. There is a large descrepancy in output between the two. The A600 running the two front 4X6's is very strong and the second A600 running any kind of speaker is roughly half the first.
Both have 13.5 voltage sometimes 14 at vehicle startup. In addition the strong A600 (powering the 2 4x6's) gets extremely hot and makes a low grade buzzing noise fom inside the amp. Both amps display the normal LEDS with no yellow leds on. The strong amp works great and sounds great but I am concerned about the heat and noise. The other A600 stays cool but just doesn't put out. I have swapped RCA's and speakers....no difference. I also am running an A1200 which is working fine. All amps have their own seperate short grounds and power supplies which are 8 guage.
Can someone help me out? Is my alternator the problem? How can I diagnose this problem? I do I repair it?
i know this is a super old thread but i just thought it was worth a bump..heh...i find it interesting learning about some of the history behind these things...
i still have 2 working Blue Thunder PRO 504 amplifiers in working condition...
i also have another 10 or so Blue Thunder PRO 504's on the shelf waiting for me to repair them.....
i still have 2 working Blue Thunder PRO 504 amplifiers in working condition...
i also have another 10 or so Blue Thunder PRO 504's on the shelf waiting for me to repair them.....
turbo_slug said:
Eh, those Blue Thunders aren't old enough. Try 1991 MTX Amps. They were long and finned like most old amplifiers were. PPI only made the Blue Thunder then while Orion built the Terminator for Mitek. That was also when MTX had 2 ohm woofers and subwoofers (and you thought Orion was the first!)
The Blue Thunder amps are so similar to the Thunder amps that its almost ridiculous to draw a distinction between them - but that's what Mitek did for years. The BT is not a better amp than the Thunder series, just uglier (IMO) and more expensive. When MTX came out with the BT with the blinding bright blue LED (say that 3x fast) and the "globetrotter" emblem, I think I threw up a little in my mouth.
Easy to repair - in most cases the RCA shield connection breaks off leaving the amp to motorboat in an astable state (whump whump whump...)
So, this thread is old...what was the original question? LOL.
sorry to bring back an old thread but i am getting frustrated trying to repair MTX amps. can someone post pictures of the "RCA shield connection breaks off leaving the amp to motorboat in an astable state" and the best way to check for this and to repair it?
i am aware of some of the design differences between MTX and conventional amps and have repaired a few in the past however i have several that have either very little audio with a huge hum on the outputs or just the hum and no audio. the power supply fets and outputs seem to check fine in the circuit and i cant see an obvious problem with the rca's. i like the quality and power of MTX amps when they are working but it seems that when they fail they are harder than most to repair. hardly ever just bad outputs and/or power supply fets and all of those darn smt parts don't make things any easier.
also are there any other common known problems with MTX amps that i may be missing or unaware of and how to check for them?
i thought i was up to the MTX repair level but i might not be there yet! i guess my old broken x-tant amps will really have to wait in that case
i am aware of some of the design differences between MTX and conventional amps and have repaired a few in the past however i have several that have either very little audio with a huge hum on the outputs or just the hum and no audio. the power supply fets and outputs seem to check fine in the circuit and i cant see an obvious problem with the rca's. i like the quality and power of MTX amps when they are working but it seems that when they fail they are harder than most to repair. hardly ever just bad outputs and/or power supply fets and all of those darn smt parts don't make things any easier.
also are there any other common known problems with MTX amps that i may be missing or unaware of and how to check for them?
i thought i was up to the MTX repair level but i might not be there yet! i guess my old broken x-tant amps will really have to wait in that case
shagone said:sorry to bring back an old thread but i am getting frustrated trying to repair MTX amps. can someone post pictures of the "RCA shield connection breaks off leaving the amp to motorboat in an astable state" and the best way to check for this and to repair it?
i am aware of some of the design differences between MTX and conventional amps and have repaired a few in the past however i have several that have either very little audio with a huge hum on the outputs or just the hum and no audio. the power supply fets and outputs seem to check fine in the circuit and i cant see an obvious problem with the rca's. i like the quality and power of MTX amps when they are working but it seems that when they fail they are harder than most to repair. hardly ever just bad outputs and/or power supply fets and all of those darn smt parts don't make things any easier.
also are there any other common known problems with MTX amps that i may be missing or unaware of and how to check for them?
i thought i was up to the MTX repair level but i might not be there yet! i guess my old broken x-tant amps will really have to wait in that case
Eh, they're not that bad - but I haven't worked on the new ones with SMT devices. But, the topology probably hasn't changed much. It's just a complementary bipolar amp connected to an all N-channel output stage. The "motorboating amp" thing is simply that the RCA connectors (signal input) break the common ground pin under the connector leaving the input stage wondering what to do. It commonly sends large DC transients through the speaker causing blown fuses...or popping sounds. Repairing this (at least on the old ones) was as simple as soldering a thin wire between the connector and PC board - no more flex breakage.
Xtant amps are even easier - they're just mixed SMT/TH technology with tons of repetitive circuitry. However the 1001d can clean your clock, troubleshooting-wise. I prefer to avoid them - especially since I've never had a schematic for any Xtant (or MTX, for that matter).
BTW, when replacing FETs in an MTX, they must be from the same lot (date code) or biasing will be unstable.
Perry Babin said:
Thanks Perry.
This looks like it would be hard to spot from the outside if the plastic casing is covering the part where the sheild goes into the board. i guess a quick continuity check would work unless it was an intermittent connection. would the housing move more than normal if this point was broken? i'm guessing it might?
Perry Babin said:
I noticed that some of the newer Rockford amps have metal RCA housings like these but i don't remember what series of MTX amps have them. Either way if i ever open up an amp of any type and see them I think I'll start soldering them just for security.
Thanks for the tips guys. Are there any other problems unique to MTX amps i should look out for?
Perry, I know that most of this info may be in your tutorial DVD that I already have but there is just so much info that i have not had time to go through it all.